Peter Paul Rubens (1577–1640) and Anthony van Dyck (1599–1641): Works on Paper – The Metropolitan Museum of Art https://www.metmuseum.org/essays/peter-paul-rubens-1577-1640-and-anthony-van-dyck-1599-1641-works-on-paper
Rubens and van Dyck are among the finest draftsmen of all times. The works they left behind probably count, respectively, some 700 and 200 sheets.
This stage would be followed by chalk studies from the live model, not in trois crayons